未打穿散体材料桩复合地基固结解析研究

继续发展考虑应力集中效应的未打穿散体材料桩复合地基固结解析理论,并分析此类地基的固结基本性状。研究表明,根据本文提出的数学模型,桩体渗透性、桩体刚度和打穿度对地基的固结速率有较大影响;沿用竖井固结理论进行计算得到的平均固结度较本文理论的计算结果偏小。     

高速公路软土地基固结系数反分析

基于地基固结理论,提出了考虑地基加固区下卧层修正的沉降资料反演固结系数的计算方法。结合通启高速公路沉降资料,反算出固结系数,相对室内固结试验成果高出1~2个数量级。并应用于计算路基沉降,与实验室测得的固结系数计算的沉降曲线进行对比和分析,得出了一些结论和建议。     

Combining pickups and deliveries in vehicle routing – An assessment of carbon emission effects

This paper studies the effect on carbon emissions of consolidation of shipments on trucks. New positioning and communication technologies, as well as decision support systems for vehicle routing, enable better utilization of vehicle capacity, reduced travel distance, and thereby carbon emission reductions. We present a novel carbon emission analysis method that determines the emission savings obtained by an individual transport provider, who receives customer orders for outbound deliveries as well as pickup orders from supply locations. The transport provider can improve vehicle utilization by performing pickups and deliveries jointly instead of using separate trucks. In our model we assume that the transport provider minimizes costs by use of a tool that calculates detailed vehicle routing plans, i.e., an assignment of each transport order to a specific vehicle in the fleet, and the sequence of customer visit for each vehicle. We compare a basic set-up, in which pickups and deliveries are segregated and performed with separate vehicles, with two consolidation set-ups where pickups and deliveries may be mixed more or less freely on a single vehicle. By allowing mixing, the average vehicle load will increase and the total driven distance will decrease. To compare carbon emissions for the three set-ups, we use a carbon assessment method that uses the distance driven and the average load factor. An increase in the load factor can reduce part of the emission savings from consolidation. We find that emission savings are relatively large in case of small vehicles and for delivery and pickup locations that are relatively far from the depot. However, if a truck visits many demand and supply locations before returning to the depot, we observe negligible carbon emission decreases or even emission increases for consolidation set-ups, meaning that in such cases investing in consolidation through joint pickups and deliveries may not be effective. The results of our study will be useful for transport users and providers, policymakers, as well as vehicle routing technology vendors.     

改进有序组合树法在铁路普通零担货物拼箱配装中的应用

为优化铁路普通零担货物拼箱配装方案,以集装箱标记载重最大化为目标,建立0—1整数规划模型,利用改进的有序组合树算法对模型进行求解,得出最优拼箱配装方案。通过拼箱配装实例的计算,说明该算法解决零担拼箱配装问题具有一定的有效性和优越性。     

塑料排水板渗透率的确定和要因分析

针对软土地带地下渗流严重的问题,采用排水固结塑料板渗透率的确定进行分析,寻找合适的控制参数.     

喷射混凝土施工在双曲拱桥加固中的应用

简述了喷射混凝土施工在双曲拱桥加固中的操作规程和注意事项.     

临空条件下铁路顺层边坡的加固设计

通过总结渝怀铁路、株六铁路、内昆铁路等铁路顺层边坡处理工点的成功经验及失败教训,论述可能产生顺层滑动的几种情况以及设计应注意的问题。首次提出顺层情况下二面临空及三面临空的概念,应特别注意二面临空及三面临空情况下更容易发生顺层滑动。论述顺层边坡开挖的影响范围问题,分析总结相应的加固处理措施。     

浅谈梁式桥的加固

介绍了几种梁式桥的加田方法,可供有关管理部门及施工单位在实际应用中参考.     

高铁CFG桩—筏复合地基固结解析解及特性

考虑桩—土在刚度、渗透性等方面的差异,建立端承型CFG桩—筏复合地基轴对称固结模型,推导桩间土的固结方程,并给出"单级等速加载"情况下固结方程的解析解;应用该解析解结合工程实例进一步研究置换率、桩—土压缩模量比、加荷速率地基设计参数对固结特性的影响.结果表明:桩的作用增大复合地基等价固结系数,固结速率随置换率、桩—土压...     

Evaluating the environmental impacts of online shopping: A behavioral and transportation approach

Various fields and commercial sectors have witnessed a transformation with the advent of the internet. In the last decade, the retail sector in particular has witnessed the massive growth of e-commerce. This has also significantly altered our shopping experiences, influencing a range of decisions, from where, how, and how much to shop. With the consistent growth of e-commerce transactions, more trucks than ever before are entering cities today, bringing with them the negative externalities of increased congestion and pollution. This study first unravels underlying shopping behaviors–both in-store and online–using the 2016 American Time Use Survey (ATUS) data. The authors also develop an econometric behavioral model to understand the factors that affect shopping decisions. At a macro level, the disaggregate individual shopping behaviors are studied by implementing the model to synthetic populations to estimate potential vehicle miles traveled and environmental emissions in two metropolitan areas, Dallas and San Francisco (SF). Finally, the study estimates the impacts of rush deliveries, basket size, and consolidation levels by developing a breakeven analysis between in-store and online shopping. These results confirm the importance of managing the urban freight system, including delivery services and operations, to foster a more sustainable urban environment.